size = int(input("请输入棋盘的大小："))
for i in range(size):
    for j in range(size):
        if i == 0 and j == 0:
            print("┏",end = '')
        elif i == 0 and j == size - 1:
            print("┓",end = '')
        elif i == size - 1 and j == 0:
            print("┗",end = '')
        elif i == size - 1 and j == size - 1:
            print("┛",end = '')
        elif j == 0:
            print("┠",end = '')
        elif i == size - 1:
            print("┷",end = '')
        elif j == size - 1:
            print("┨",end = '')
        elif i == 0:
            print("┯",end = '')
        else:
            print("┼",end = '')
    print('')